1. Field of the Invention
The present invention relates to the composition in the form of wash, rinse, soak, paste, gel, aerosol spray, or other suitable delivery system and method for the prevention of oral diseases with the use of stabilized chlorine dioxide and establishing the bactericidal properties at a concentration range of about 0.005 to about 0.800% (w/v) to significantly reduce bacterial accumulation and to act as an antimicrobial on both gram-negative anaerobic/aerobic/facultative and gram-positive anaerobic/aerobic/facultative oral bacteria in plaque and polymicrobial dental biofilm environments.
2. Description of Related Art
Dental plaque is a diverse community of microorganisms found on the tooth surface embedded in an extracellular matrix of host and microbial polymers. Dental plaque can occur above (supragingival) and below (subgingival) the gumline. Plaques that form on subgingival tooth surfaces and coat the epithelium lining of the gingival crevice lead to the development of periodontal infections (i.e., gingivitis and periodontitis).
Supragingival dental plaque forms on teeth within hours after they are cleaned. In the presence of a diet rich in sucrose, shifts occur in the supragingival plaque to more of an acidogenic plaque, with dental caries as an outcome. Salivary proteins such as mucins, proline-rich proteins, staherins, histatins, and cystatins have a strong affinity for the hydroxyapatite mineral of teeth. These proteins quickly bind to hydroxyapatite of the tooth to form a thick coating called the acquired pellicle. Certain bacteria in the oral cavity selectively adhere to the pellicle, begin to divide, and form microbial communities. Initially, approximately 80% of the bacteria that colonize pellicle-coated tooth surfaces are facultative, gram-positive, non-motile cocci, such as Streptococcus (sanguis) sanguinis (U.S. Pat. No. 4,889,714). The other 20% include a variety of gram-negative bacteria such as Veillonella species. As the microbial communities grow, the environment changes due to the metabolic activities of these early colonizers and the addition of diverse groups of other bacteria to the plaque mass. An important environmental change in the plaque is the development of a low-oxygen environment that promotes the colonization and growth of anaerobic bacteria. Microorganisms in the plaque synthesize a slime matrix or glycocalyx from abundant polysaccharides, glycoproteins, and dietary sugars (e.g., sucrose) present in the oral environment. Eventually, the plaque becomes a characteristic dental biofilm with a highly structured, matrix-embedded, diverse microbial population altering gene expression severely.
Bacteria in dental biofilm are the major cause of several oral diseases including gingivitis, chronic and aggressive periodontitis, and necrotizing periodontal diseases. Gingivitis is the gingival inflammation without loss of connective tissues around teeth caused by undisturbed dental biofilm. Studies have shown that gingivitis will develop within 10-21 days without oral hygiene practices allowing for the accumulation of plaque. Approximately 80% of U.S. adults have a case of gum/periodontal disease. Gingivitis is preventable by routine oral care, but if untreated may lead to a severe gum disease known as periodontitis. Periodontitis is characterized by a group of infections which destroy supporting tissue and bone by plaque-induced inflammation. Chronic periodontitis is the most common form affecting approximately 20% of the adult U.S. population. Symptoms include the formation of deep periodontal pockets, gingival recession, increased tooth mobility, and loss of bone as detected by radiographs. If left untreated, periodontitis can lead to tooth loss.
A review of bacterial interactions in dental biofilm completed by Hojo, et al. (2009) shows the diversity of bacterial communities in dental biofilms. First colonizers, including Streptococcus sanguinis, adhere to teeth allowing for other planktonic bacteria, which are unable to adhere to teeth, to attach to it and begin colonizing, eventually developing into a biofilm. The bacterial co-aggregation on the tooth surface causes the behavioral change including increased resistance toward topical antimicrobial agents and decreasing efficacy. Hojo et al. describes further that the complexity physically restricts the antimicrobial agents due to less sensitivity developed by the polymicrobial biofilm.
Supporting evidence confirms that the present invention acts as an antimicrobial against both gram-negative anaerobic/aerobic/facultative and gram-positive anaerobic/aerobic/facultative oral bacteria in polymicrobial dental biofilm environments.
The term chlorine dioxide is widely used in the industry. Those skilled in the art will and do appreciate the various forms or variations thereof, which are available to perform certain intended functions and purposes. Furthermore, U.S. Pat. No. 3,271,242 describes a form of stabilized chlorine dioxide and a method of making the product, which is particularly useful in carrying out the present invention.
The use of chlorine dioxide for sanitation was first suggested in 1948 by Eric Woodward to reduce the incidence of unpleasant taste in shrimp. Since then, chlorine dioxide [ClO2] use has spread into a number of other industries. The oxidative power of ClO2 is used in the manufacturing of wood pulp as an agent for the bleaching of cellulose fibers. In water treatment, ClO2 has become widely used for water sanitation. In this case, it has been shown to be effective at reducing the bacterial content, algae content, and odor associated with wastewater treatment. Additionally, the utilization of ClO2 for treating drinking water has been effective without adversely affecting its taste. The benefits of ClO2 over other processes utilizing ozone or bleach for example, are reduced cost, reduced toxicity and reduced production of chlorinated by-products.
In 1999 the EPA published “Alternative Disinfectants and Oxidants Guidance Manual,” describing disinfectant uses for ClO2 and containing information on the mechanism of generation, application and standards and regulations governing use of ClO2 and other disinfectants. Major applications listed by table 4-5, section 4.8.2 in the manual are as follows: primary or secondary disinfectant, taste control, odor control, TTHM/HAA reduction (total trihalomethanes are chlorinated organics, chloroform [CHCl3] and dichlorobromomethane [CHCl2Br] for example; haloacetic acids are created when an atom from the halogen group, chlorine, for example, replaces a hydrogen on the acetic acid molecule), Fe and Mn control, color removal, sulfide destruction, phenol destruction and Zebra mussel control [EPA 1999, p. 4-34]. These are accomplished by oxidation of various substances found in water. For example, unpleasant tastes and odors (sulfides, phenols, others) can exist in water due to vegetative decay and algae content. ClO2 reduces these tastes either by eliminating the source (algae) or oxidizing the causative taste and odor molecules. In the control of iron and manganese, ClO2 will bring the dissolved ions out of solution to form precipitates, which may be eliminated through filtration and/or sedimentation. Zebra mussel control is important because it helps to maintain the natural ecology of a body of water. Zebra mussels are organisms that will infest a lake or river, strip it of nutrients and create a pseudo-fecal mucous layer on the bottom. The use of ClO2 for water sanitation and pulp treatment generally involves on-site generation followed by immediate use.
The term ‘stabilized chlorine dioxide’ on the other hand, refers to the generation and subsequent sequestration of ClO2, which allows for its storage and availability for later use. The first reference to stabilized chlorine dioxide in a patent was in U.S. Pat. No. 2,482,891 in which ClO2 is stabilized in a powder for storage. For its application, it is mixed with water to “liberate” the chlorine dioxide. A method and composition for the use of aqueous stabilized chlorine dioxide for antiseptic purposes was noted in U.S. Pat. No. 3,271,242. The 1979 text Chlorine Dioxide, Chemistry and Environmental Impact of Oxychlorine Compounds, describes (aqueous) stabilized chlorine dioxide as follows:                “The stabilization of chlorine dioxide in aqueous solution was proposed by using perborates and percarbonates. Thus, a stabilized solution of ClO2 would be obtained at pH 6 to 8 by passing gaseous ClO2 into an aqueous solution containing 12% Na2CO3.3H2O2. Other variants are possible. In reality, it seems that in these methods, the chlorine dioxide is practically completely transformed to chlorite. Dioxide is released upon acidification.” [Masschelein, 1979]        
The reference to percarbonates and perborates may be replaced by the term ‘peroxy compounds,’ which would refer to any buffer suitable for maintaining the pH and hence, the stability of the ClO2 in solution. The buffer is a necessary component, as the ClO2 is unstable at low pH. Once the solution reaches low pH or encounters an area of low pH, the stabilized ClO2 is released from solution and available for sanitation and oxidation.
In oral care products, the use of stabilized ClO2 has been suggested as an active ingredient by a number of U.S. Pat. Nos. 4,689,215; 4,696,811; 4,786,492; 4,788,053; 4,792,442; 4,793,989; 4,808,389; 4,818,519; 4,837,009; 4,851,213; 4,855,135; 4,886,657; 4,889,714; 4,925,656; 4,975,285; 5,200,171; 5,348,734; 5,489,435; 5,618,550. Additionally, the use of stabilized ClO2 has been suggested for the degradation of amino acids in U.S. Pat. No. 6,136,348. The premise for these products is that the stabilized chlorine dioxide will remain as such until it encounters the localized reductions in pH. Reduced pH levels can be a result of low pH saliva or oral mucosa, the accumulation of oral disease-causing bacteria or the presence of plaque biofilms on teeth and epithelial cells. Once released, the now active chlorine dioxide is effective at killing bacteria and oxidizing VSCs. Data have shown dramatic reduction in bacteria after exposures as short as 10 seconds, as set forth in U.S. Pat. No. 4,689,215. Additional data show remarkable decrease in VSCs in expired mouth air; the mechanism is believed to be oxidation of VSCs through the cleavage of the sulfide bonds.
The present invention relates to a composition containing stabilized chlorine dioxide that may be used for treatment of the mouth either in a solution, for example as a mouthwash, in concentrations below approximately 0.800% (w/v) for the control of disease-causing bacteria, bacterial plaque, and oral malodor. The rinse may be flavored with the addition of mint oils or extracts. The flavoring would not interact with stabilized chlorine dioxide or affect the stability of the formulation.
For liquids such as mouthwash, the standard unit of measurement when expressing concentration is weight-volume percentage. That is, a certain weight of component, solid, liquid, or dissolved in a solvent, is present in a certain volume of total mouthwash. Preferred concentrations of stabilized chlorine dioxide in this invention are in the range of 0.005% to 0.800% (w/v).
By “topical oral care composition” or “oral composition” as used herein is meant a product which is not intentionally swallowed for purposes of systemic administration of therapeutic agents, but is retained in the oral cavity for a sufficient time to contact substantially all of the dental surfaces and/or oral mucosal tissues for purposes of oral activity.
Previous inventions contemplate the use of stabilized chloride dioxide as a bactericide for the treatment gingivitis as well as a deodorizing agent for the treatment of oral malodor (Ratcliff, U.S. Pat. No. 4,689,215; Madray, U.S. Pat. No. 6,231,830; Richter, U.S. Pat. No. 5,738,840; Witt, U.S. Pat. No. 6,350,438). There is a large amount of evidence that indicates chlorine dioxide has bactericidal properties and that the chlorine dioxide serves to attack malodorous volatile sulfur compounds (VSC) in the mouth by splitting of the sulfide bonds (Lynch, 1997; Silwood, 2001).
Prior art compositions that have been used and tested have been accepted to an extent of efficacy in treating or preventing periodontitis, gingivitis, plaque accumulation and mouth odor. Prior Ratcliff patents have demonstrated the bactericidal effect of stabilized chlorine dioxide on Streptococcus sanguinis (U.S. Pat. Nos. 4,851,213 and 4,889,714). It is directed to a method of reducing dental plaque by altering the ecology of oral bacteria over a period of ten seconds by means of reducing the bacterium S. sanguinis by more than 90%. It also describes how the method breaks down double bonds in the glucosyltransferases present in the oral cavity.
Concentration range between 0.005-0.5% (w/v) chlorine dioxide with about 0.02%-3.0% phosphate is preferred in U.S. Pat. No. 5,348,734 by Ratcliff. This is the highest recited range in the prior art. The present invention is an extension with evidence that higher concentrations of stabilized chlorine dioxide are bactericidal for oral bacteria at a faster rate and in complex microbial environments, dental biofilm, than taught in the prior art.
Periodontal disease results from response to the polymicrobial ecology of subgingival plaque. The diverse and complex ecology of the oral cavity leads to a more resistant response to the immune system and antimicrobial drugs. In order to investigate a more natural environment of the oral cavity with periodontal disease, it is important to develop experimental conditions that mimic the diversity and complexity of the bacterial ecology. A limited number of studies that demonstrate considerable bacteria kill and inhibition of dental biofilm development on such microbial environments exist. The present invention takes into consideration the diverse natural ecology and investigates both the bactericidal properties in mixed microbial biofilms of several oral bacteria involved in periodontal diseases. Previous developments and prior research involve the investigation of single bacterial suspension cultures, which do not accurately represent the natural oral ecology on plaque development and dental biofilm.
The current invention is a continuation of related prior art research presented by Villhauer et al (2008). It contemplates the use of stabilized chlorine dioxide as a bactericidal and bacteriostatic agent against microorganisms involved in oral disease such as, but not limited to, Porphyromonas gingivalis, Actinomyces odontolyticus and A. viscosus, Prevotella intermedia, Fusobacterium nucleatum, Micromonas micros, Streptococcus sanguinis and S. oralis, Campylobacter rectus, and Enterococcus faecalis. The research shows bactericidal activity of the stabilized chlorine dioxide against a spectrum of oral bacteria, as single bacteria and as polymicrobial communities, associated with periodontal diseases and health. Polymicrobial biofilms of oral bacteria and the affect of stabilized chlorine dioxide solution as a bactericidal agent has also been examined.
U.S. Pat. No. 6,696,047 recites oral care compositions containing 0.02% to 6.0% of the chlorite ion at alkaline pH which are essentially free of chlorine dioxide (less than 2 ppm of chlorine dioxide)—and the novelty of these compositions are that the prescribed formulations are claimed to maintain stable amounts of the chlorite ion at 25° C. for one year or 40° C. for 3 months. According to the teachings in the patent, stability is exhibited in the composition if the following is observed at 25° C. for one year and/or 40° C. for three months: the chlorite ion is delivered in efficacious amounts to the oral cavity, the composition does not degrade to form chlorine dioxide, and the composition does not degrade excipients (with a change in flavor being a major indicator of degradation). A quantifiable percentage of acceptable chlorite ion degradation from time zero is not explicitly defined in the patent for any embodiment. The sample formulations that are presented to show stability of various embodiments (presented in the table labeled ‘Results of Stability Testing’) are all prepared at pH 10. Chlorite ion concentration, pH and flavor concentration are measured to demonstrate stability of the formulations. The compositions in U.S. Pat. No. 6,696,047 are designed for human and animal subjects, and while not specifically claimed in claims, the text of the patent indicates that these compositions may be used to treat and prevent diseases of the oral cavity, including caries. However, no claim is made that the composition without additional therapeutic agents has antimicrobial effects against polymicrobial dental biofilms in the oral cavity.
Biofilm growth is also a problem which occurs in dental unit water lines (DUWL). Some of the microbe genera detected in DUWL biofilms are Actinomyces, Bacillus, Mycobacteria, Pseudomonas, Sphingomonas, Staphylococcus, and Streptococcus. Stabilized chlorine dioxide solutions have been previously shown to be an effective decontaminant on biofilms that form in DUWLs. A specific study yielded results that indicated that stabilized chlorine dioxide outperformed alkaline peroxide in managing biofilm growth, by retaining a heterotrophic plate count (HPC) value of 0 after 5 days of treatment (Wirthlin et al., 2003).
There is no prior art that show evidence of antimicrobial properties of stabilized chlorine dioxide composition in the concentration range of about 0.005% to about 0.800% (w/v) on gram-negative anaerobic/aerobic/facultative and gram-positive anaerobic/aerobic/facultative oral bacteria in polymicrobial dental biofilm environments occurring in the oral cavity or with in vitro or in vivo experiments.